In order for urban water to be suitable for agricultural irrigation, it undergoes an advanced treatment process that removes contaminants and pathogens. But how is its quality ensured and what technologies are used?
Obtaining reclaimed urban water suitable for reuse requires additional, more advanced treatments to reduce the residual contaminant load, suspended solids and turbidity, as well as pathogenic microorganisms (viruses and bacteria) to ensure the sanitary quality of the water.
Tertiary treatments are usually carried out in the same WWTP facilities, after secondary treatment, in the section known as the Water Regeneration Plant (WRP).
The choice of tertiary treatments depends on two factors:
– Existing primary and secondary treatment lines in the WWTP.
– Required quality of the reclaimed water, in order to comply with the minimum quality standards for use under current legislation.
All these tertiary processes for reuse are generally based on different combinations of technologies, which vary in complexity and investment cost:
Physical-chemical:
Coagulation, flocculation and decantation
Deep filtration
Surface filtration
Dissolved air flotation
Advanced oxidation
Filtration membranes:
Microfiltration
Ultrafiltration
Nanofiltration
Reverse osmosis
Electrodialysis
Disinfection:
Ultraviolet radiation
Chlorine: mainly sodium hypochlorite
Ozone
What tertiary treatments are used in the 15 I-ReWater pilot plants?
1.- Lúpulo Abegondo (Galicia): UVV disinfection
2.- Lúpulo Cubillos del Sil (Castile and León): Microfiltration with self-cleaning mesh filter + UV disinfection
3.- Mirandela Olive Grove (North): Mechanical filtration + UV disinfection
4.- Alfândega da Fe Almond Grove (North): Mechanical filtration + UV disinfection
5.- Herdade do Esporão Vineyard (Alentejo): Trial in the process of adjustment as the initial approach needs to be reviewed.
6.- Monte da Ravasqueira vineyard (Alentejo): Trial in the process of adjustment as the initial approach needs to be reviewed.
7.- Carrión de los Céspedes olive grove (Andalusia): SBN (artificial wetlands working under different configurations) + Storage lagoon + Ultrasound + Sand and mesh filtration
8.- Carrión de los Céspedes tomato (Andalusia): Storage lagoon + Ultrasound + Sand and mesh filtration
9.- Maials almond tree (Catalonia): Simulation of the chemical composition of reclaimed water
10.- Hortícolas Viladecans, watermelon (Catalonia): Membrane bioreactor (MBR) + Chlorination
11.- La Grajera vineyard (La Rioja): Water comes from secondary treatment (MBR membrane filtration) at the WWTP
12.-Hops Lot-et-Garonne (Nouvelle Aquitaine): Possible simulation of the chemical composition of reclaimed water
13.- Hops Taizé-Aizie (Nouvelle Aquitaine): Study only with water deficit due to organic farming
14.- Roquefort-des-Corbières vineyard (Occitanie): Mechanical filtration of 40 µm + 400 m³ tarpaulin + low-pressure UV + chlorination + 50 m³ tarpaulin
15.- Gruissan vineyard (Occitanie): 3,000 m³ reserve + sand filtration + low-pressure UV + chlorination
